Here's a helpful breakdown that I think clarifies the generation gaps a little more than the mainstream, broader definitions:
Boomers: Born post-war through about 1955 or so. Adolescents or teens during 60s cultural revolution. Embodies all the stereotypical Boomer qualities.
Generation Jones: Born from late 50s to early 60s. In elementary school or toddlers during 60s cultural revolution. Embodies some Boomer tendencies (blind trust of major institutions/mainstream media), less so others (Me-generation cultural narcissism, spend-it-all-before-I-die), but also not quite Gen X, lacking their pessimism and cynicism.
Gen X: Children mostly of Boomers, born in 70s. Bore full brunt of no-fault divorce. Cynical and distrusting, skeptical of institutions. Cultural rise in early 90s with alternative music scene.
Gen Y: Children mostly of Jones-ers, born in 80s. Hyper-nostalgic, heads buried in sand, consoomerism. Cultural rise in mid-2000s with first gen social media, Hipster subculture.
Millennials: Children of Jones-ers, some Boomers, some early Xers. Highly impressionable, molded totally by institutions, SJWs, Year Zero adherents. Cultural rise in early-mid 2010s, SJW movement.
We remember the 60s for the cultural and sexual revolution, but only the older part of the generation called Boomers experienced it. My parents, born about 1960, were way too young to have absorbed anything from the sexual revolution in the 60s; but their older siblings are extremely Boomer.
It's the same thing in the 90s. We think of the 90s as the rise of Gen X cynicism, Grunge, rap culture, and all that stuff. But kids from my generation, now in their mid-30s, didn't actually experience any of that because we were kids, only catching the tail end (the rise of rap, Nu-Metal.) We were kids when Grunge, a Gen X movement, was going on. 9/11 was our formative event. Millennials, probably the election of Barack Obama or the debut of the iPhone - or maybe the Martyrdom of St. Trayvon. But again, Gen Y's defining feature is probably a childhood and/or adolescence bifurcated between a more "traditional", analogue experience, and the rise of ubiquitous consumer PC tech.
The transition years (1960-1965, 1990-1995) are interesting because people born in this period tend to exhibit a blend of qualities between the generations that can vary quite widely. I'm majority Gen Y (born 1988), but do have some Millennial qualities. My brothers, born between 90-95, have a more even blend. People I know born 1995-2000, though, are definitively in the Millennial camp. I don't know Gen Z well enough to comment much on them, aside from older Zoomers seeming quite similar to Millennials, and younger ones either being hyper-Millennial or hyper-based reactionary types.
In the mid 2010s I was part of a house church group where the majority of my peers were about five years or more younger than me, putting them firmly in the Millennial contingent. At the time I was unaware of all this generational theory stuff, but I was struck by how jarringly different their outlook and experiences were compared to my own and couldn't really relate much to them. Maybe generational theory seems like hair-splitting on the surface but it actually helps us understand the cultural evolution (or more aptly, de-volution) and how we relate to each other across generations a little better.
I recently realized that a couple of YouTube channels I enjoy, LGR
(which covers retro computing) and Doug DeMuro
(cars, with a pronounced interest in quirky vehicles and "new retro" cars of the 80s and 90s) are both almost exactly the same age as me and exhibit rather pronounced Gen Y tendencies.